Transmission Components - Jeep 1987 Wrangler Workshop Manual

AUTOMATIC TRANSMISSION
GENERAL INFORMATION
GENERAL SERVICE INFORMATION
The Model 999, three speed, automatic trans-
mission is used in Wrangler/YJ models.
This section covers removal, installation, lubri-
cation and in-vehicle service and adjustment
procedures for the Model 999 automatic
transmission.
The procedures, specifications and special
tools needed to overhaul the Model 999 trans-
mission are contained in the T.A. 700/900 Com-
ponent Service Manual.
TRANSMISSION COMPONENTS
The Model 999 is a three speed, automatic
transmission with a compound planetary gear
system. A shift lever and linkage is used to se-
lect desired drive range. Transmission shift
points are controlled by an externally mounted
throttle linkage. The transmission case and
converter housing are a one-piece aluminum
casting. An aluminum adapter housing con-
nects the transmission to the transfer case
models.
The Model 999 has two multiple disc clutches
(3-4), two bands and actuating servos (7-18), an
overrunning clutch (8) and two planetary gear
sets (5-6). These components provide one re-
verse and three forward gear ranges. The plan-
etary gear sets (5-6) are connected by a com-
mon sun gear. The sun gear is interconnected
to the multiple disc clutches through the driving
shell (16) which is splined to the sun gear and
front clutch retainer.
The hydraulic system consists of a single oil
pump (2), a valve body (15) containing the pres-
sure regulatingshift control valves, a governor
valve (9), two servos and a three element tor-
que converter.
The transmission fluid is cooled by circulating
the fluid through an external cooler built into the
radiator lower tank. Transmission fluid is
filtered by a Dacron element filter attached to
the valve body.
The transmission is vented through a passage
drilled into the upper portion of the oil pump
housing.
F-5